The out side of the frame is
310mm and the in side is 241mm. at this point you have two :-
Options 1. VFR400 swing arm due to it bolts to the frame not the engine which is 13mm. make up a 13mm spacer and arm will bolt in ( a few things to ponder over - single nut on wheel / limited wheel stile , smaller tyre option )
Option 2. use a VFR750/800 swing arm, space frame out to 288 inside of the frame which means cutting the frame and insetting spaces of 23.5mm each side, to do this you need a jig…? So before you cut the frame you make a fig first then cut the frame and with a large lever pry out and insert the spaces in and bolt up.
![Image](http://img161.imageshack.us/img161/5430/sbike009ft8.th.jpg)
The back engine mounts are made from aluminium about 10mm thick with a aluminium tube welded to the two engine mounts which in turn is welded to the upper frame/shock mount and to the lower link arm frame, so the engine / swing arm and frame is tide together to give a stiffer and less flex.